WO2019087487A1 - 有機酸及び排泄物の回収方法、及びリサイクルパルプ繊維の製造方法 - Google Patents
有機酸及び排泄物の回収方法、及びリサイクルパルプ繊維の製造方法 Download PDFInfo
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- WO2019087487A1 WO2019087487A1 PCT/JP2018/028146 JP2018028146W WO2019087487A1 WO 2019087487 A1 WO2019087487 A1 WO 2019087487A1 JP 2018028146 W JP2018028146 W JP 2018028146W WO 2019087487 A1 WO2019087487 A1 WO 2019087487A1
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- WIPO (PCT)
- Prior art keywords
- organic acid
- aqueous solution
- acid
- water
- excrement
- Prior art date
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- 150000007524 organic acids Chemical class 0.000 title claims abstract description 339
- 238000000034 method Methods 0.000 title claims abstract description 91
- 239000000835 fiber Substances 0.000 title claims description 82
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- 238000011084 recovery Methods 0.000 title abstract description 7
- 239000007864 aqueous solution Substances 0.000 claims abstract description 298
- 150000003839 salts Chemical class 0.000 claims abstract description 146
- 229910052751 metal Inorganic materials 0.000 claims abstract description 87
- 239000002184 metal Substances 0.000 claims abstract description 87
- 239000002253 acid Substances 0.000 claims abstract description 80
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 62
- 239000007787 solid Substances 0.000 claims abstract description 57
- 239000000203 mixture Substances 0.000 claims abstract description 53
- 238000001556 precipitation Methods 0.000 claims abstract description 44
- 239000002250 absorbent Substances 0.000 claims abstract description 32
- 229920000247 superabsorbent polymer Polymers 0.000 claims description 91
- 230000002779 inactivation Effects 0.000 claims description 83
- 230000001954 sterilising effect Effects 0.000 claims description 62
- 238000004659 sterilization and disinfection Methods 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 35
- 230000002745 absorbent Effects 0.000 claims description 30
- 238000010979 pH adjustment Methods 0.000 claims description 29
- 230000000415 inactivating effect Effects 0.000 claims description 28
- 239000000243 solution Substances 0.000 claims description 24
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 23
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 21
- 238000010494 dissociation reaction Methods 0.000 claims description 21
- 230000005593 dissociations Effects 0.000 claims description 21
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 16
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 14
- 150000004697 chelate complex Chemical class 0.000 claims description 14
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 claims description 9
- 230000003472 neutralizing effect Effects 0.000 claims description 8
- 235000005985 organic acids Nutrition 0.000 claims description 8
- 230000005855 radiation Effects 0.000 claims description 8
- 239000004155 Chlorine dioxide Substances 0.000 claims description 7
- 235000019398 chlorine dioxide Nutrition 0.000 claims description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 6
- 229910017604 nitric acid Inorganic materials 0.000 claims description 6
- 230000001376 precipitating effect Effects 0.000 claims description 6
- SXDBWCPKPHAZSM-UHFFFAOYSA-N bromic acid Chemical compound OBr(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-N 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- QFWPJPIVLCBXFJ-UHFFFAOYSA-N glymidine Chemical compound N1=CC(OCCOC)=CN=C1NS(=O)(=O)C1=CC=CC=C1 QFWPJPIVLCBXFJ-UHFFFAOYSA-N 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 238000004064 recycling Methods 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 229910052788 barium Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052725 zinc Inorganic materials 0.000 claims description 4
- 229920000642 polymer Polymers 0.000 abstract description 11
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 28
- 239000007788 liquid Substances 0.000 description 23
- 238000000926 separation method Methods 0.000 description 20
- 241000894006 Bacteria Species 0.000 description 18
- 239000000428 dust Substances 0.000 description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 9
- 238000010521 absorption reaction Methods 0.000 description 9
- 235000015165 citric acid Nutrition 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- 230000001877 deodorizing effect Effects 0.000 description 7
- 150000007522 mineralic acids Chemical class 0.000 description 7
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 description 5
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical compound CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 description 4
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 4
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 4
- 238000000909 electrodialysis Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000011975 tartaric acid Substances 0.000 description 4
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 description 4
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 3
- RGHNJXZEOKUKBD-SQOUGZDYSA-N Gluconic acid Natural products OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C(O)=O RGHNJXZEOKUKBD-SQOUGZDYSA-N 0.000 description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- FNAQSUUGMSOBHW-UHFFFAOYSA-H calcium citrate Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O FNAQSUUGMSOBHW-UHFFFAOYSA-H 0.000 description 3
- 239000001354 calcium citrate Substances 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 210000003608 fece Anatomy 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 239000001630 malic acid Substances 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 3
- 235000002906 tartaric acid Nutrition 0.000 description 3
- 235000013337 tricalcium citrate Nutrition 0.000 description 3
- LNIZKKFWMDARJV-UHFFFAOYSA-H tricalcium;2-hydroxypropane-1,2,3-tricarboxylate;tetrahydrate Chemical compound O.O.O.O.[Ca+2].[Ca+2].[Ca+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O LNIZKKFWMDARJV-UHFFFAOYSA-H 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 2
- 239000004135 Bone phosphate Substances 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- RGHNJXZEOKUKBD-UHFFFAOYSA-N D-gluconic acid Natural products OCC(O)C(O)C(O)C(O)C(O)=O RGHNJXZEOKUKBD-UHFFFAOYSA-N 0.000 description 2
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 235000019253 formic acid Nutrition 0.000 description 2
- 230000002070 germicidal effect Effects 0.000 description 2
- 239000000174 gluconic acid Substances 0.000 description 2
- 235000012208 gluconic acid Nutrition 0.000 description 2
- 239000003014 ion exchange membrane Substances 0.000 description 2
- 235000011090 malic acid Nutrition 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 235000019260 propionic acid Nutrition 0.000 description 2
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 2
- 230000007420 reactivation Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 description 2
- 210000002700 urine Anatomy 0.000 description 2
- FBOUIAKEJMZPQG-AWNIVKPZSA-N (1E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol Chemical compound C1=NC=NN1/C(C(O)C(C)(C)C)=C/C1=CC=C(Cl)C=C1Cl FBOUIAKEJMZPQG-AWNIVKPZSA-N 0.000 description 1
- PXRKCOCTEMYUEG-UHFFFAOYSA-N 5-aminoisoindole-1,3-dione Chemical compound NC1=CC=C2C(=O)NC(=O)C2=C1 PXRKCOCTEMYUEG-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- JJLJMEJHUUYSSY-UHFFFAOYSA-L Copper hydroxide Chemical compound [OH-].[OH-].[Cu+2] JJLJMEJHUUYSSY-UHFFFAOYSA-L 0.000 description 1
- 239000005750 Copper hydroxide Substances 0.000 description 1
- 229920002732 Polyanhydride Polymers 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000005260 alpha ray Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000011260 aqueous acid Substances 0.000 description 1
- SRSXLGNVWSONIS-UHFFFAOYSA-N benzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1 SRSXLGNVWSONIS-UHFFFAOYSA-N 0.000 description 1
- 229940092714 benzenesulfonic acid Drugs 0.000 description 1
- 230000005250 beta ray Effects 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 229910001956 copper hydroxide Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004332 deodorization Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229940098779 methanesulfonic acid Drugs 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000001384 succinic acid Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 150000004685 tetrahydrates Chemical class 0.000 description 1
- XPDWGBQVDMORPB-UHFFFAOYSA-N trifluoromethane acid Natural products FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 1
- -1 trifluoromethane sulfone Chemical class 0.000 description 1
- 239000013026 undiluted sample Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
- C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C59/00—Compounds having carboxyl groups bound to acyclic carbon atoms and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
- C07C59/235—Saturated compounds containing more than one carboxyl group
- C07C59/245—Saturated compounds containing more than one carboxyl group containing hydroxy or O-metal groups
- C07C59/265—Citric acid
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
Definitions
- the present disclosure provides a method of recovering organic acid and excrement from an inactivated aqueous solution for superabsorbent polymer, comprising excrement and organic acid, and an organic that deactivates superabsorbent polymer from used absorbent articles.
- the present invention relates to a method for producing recycled pulp fibers while reusing acid.
- Patent Document 1 discloses a method of recovering pulp fibers from used sanitary products containing pulp fibers and super absorbent polymer, and producing recycled pulp reusable as a sanitary product, which method is used
- Used sanitary articles are pulp fibers and other articles by applying physical force to used sanitary products in an aqueous solution containing polyvalent metal ions or an acidic aqueous solution having a pH of 2.5 or less.
- the process of decomposing into materials, the process of separating pulp fibers from the mixture of pulp fibers and other materials generated in the decomposition process, and the process of treating the separated pulp fibers with an ozone-containing aqueous solution having a pH of 2.5 or less A method is disclosed characterized in that.
- the acidic aqueous solution having a pH of 2.5 or less contains an organic acid, and the organic acid is selected from the group consisting of tartaric acid, glycolic acid, malic acid, citric acid, succinic acid and acetic acid. It is described that it is at least one kind.
- the present disclosure aims to provide a method for recovering organic acid and excrement, which can recover each of the organic acid and excrement from an inactivated aqueous solution containing excrement and organic acid.
- Another object of the present disclosure is to provide a method for producing recycled pulp fibers from used absorbent articles while recovering each of the organic acid and excrement while recycling the organic acid.
- the present inventors are a method for recovering an organic acid and excrement from an inactivated aqueous solution for superabsorbent polymer, which contains an organic acid and excrement, wherein the inactivated aqueous solution contains a metal having a valence of 2 or more.
- a mixture collecting step of collecting a mixture of salt and solid excrement derived from the excrement, an acid capable of generating a free organic acid and a water-insoluble salt, and water are added to the mixture;
- the method for recovering organic acid and excrement according to the present disclosure can recover each of the organic acid and the excrement from the aqueous solution containing the excrement and the organic acid. Moreover, the method for producing recycled pulp fibers from the used absorbent article of the present disclosure can produce recycled pulp fibers while recovering each of the organic acid and excrement while reusing the organic acid. .
- FIG. 1 is a flowchart illustrating the recovery method of the present disclosure.
- FIG. 2 is a flowchart for explaining additional steps in the recovery method of the present disclosure.
- FIG. 3 is a flowchart illustrating the method for producing recycled pulp fiber of the present disclosure.
- FIG. 4 is a block diagram illustrating an example of a system 1 for implementing the present disclosure.
- FIG. 5 is a schematic view showing a configuration example of the bag removing device 11 and the crushing device 12 of FIG.
- FIG. 6 is a diagram showing the results of Examples 1 and 2.
- Non-water soluble salt relating to “non-water soluble salt” is “slightly soluble”, “very slightly soluble” or “mostly insoluble” in “General Rule 29" of the "15th Revision Japanese Pharmacopoeia” It is preferred to be classified as “very poorly soluble” or “not very soluble”, and more preferred to be classified as “mostly insoluble”.
- water-insoluble salts are prepared by adding 1 g of salt as a solute to water as a solvent and shaking vigorously for 30 seconds every 5 minutes at 20 ⁇ 5 ° C. It means that the amount of water dissolved within is as follows. ⁇ Less soluble: 100 mL or more and less than 1,000 mL ⁇ Very poorly soluble: 1,000 mL or more and less than 10,000 mL ⁇ Almost insoluble: 10,000 mL or more
- water soluble relating to “water soluble salt” is “slightly soluble”, “soluble” or “very soluble” in the “General Rule 29” of the “15th Amended Japanese Pharmacopoeia” It is preferable to be classified, more preferably classified as “soluble” or “very soluble”, and still more preferably classified as “very soluble”.
- water-soluble salt contains 1 g of salt as a solute in water as a solvent and shakes vigorously for 30 seconds every 5 minutes at 20 ⁇ 5 ° C. It means that the amount of water dissolved in is as follows. ⁇ Very soluble: less than 1 mL ⁇ Soluble: 1 mL or more and less than 10 mL ⁇ Slightly soluble: 10 mL or more and less than 30 mL Note that the following classifications are further included in “General Rule 29" of the "15th Revision Japanese Pharmacopoeia" Exists. ⁇ Slightly soluble: More than 30mL and less than 100mL
- “Inactivation” related to super absorbent polymer is preferably 50 times or less, more preferably 30 times or less, of the super absorbent polymer retaining excrement. More preferably, adjustment is made to have an absorption capacity of 25 times or less, for example, release of retained excrement, suppression of absorption of an inactivated aqueous solution and the like. The absorption capacity is measured as follows. (1) The inactivated super absorbent polymer is put into a mesh and suspended for 5 minutes to remove water adhering to the surface thereof, and the mass before drying: m 1 (g) is measured.
- a method of recovering an organic acid and excrement from an inactivated aqueous solution for superabsorbent polymer, comprising an organic acid and excrement comprising: A precipitation step of precipitating a water-insoluble salt of an organic acid by adding a metal salt containing a divalent or higher metal or a base containing a divalent or higher metal to the above-mentioned inactivated aqueous solution; A mixture collection step of collecting a mixture of the non-water-soluble salt of the organic acid and the solid excrement derived from the excrement from the inactivated aqueous solution subjected to the precipitation step; An organic solution which adds an acid capable of generating a free organic acid and a water-insoluble salt and water to the above mixture to form an aqueous solution containing the organic acid, the water-insoluble salt and the solid excrement Acid generation step, An organic acid aqueous solution acquiring step of removing the water-
- the above method when the organic acid is precipitated as a non-water-soluble salt of the organic acid and collected, the fine solid excrement can be aggregated and collected, and at the organic acid aqueous solution forming step, the organic acid And solid waste can be separated.
- liquid excrement derived from excrement can be recovered as liquid in the mixture collection step. Therefore, the above method can recover the organic acid and the excrement from the inactivated aqueous solution containing the excrement and the organic acid, respectively.
- the organic acid is less likely to form a chelate complex with the metal constituting the metal salt, and thus the organic acid
- the recoverability of the The above method is particularly useful when the organic acid is an organic acid capable of forming a chelate complex with a metal.
- the organic acid is an organic acid which does not form a chelate complex with a metal, and in the precipitation step, the water-insoluble salt of the organic acid is precipitated by adding the base to the inactivated aqueous solution. Or the method as described in 2.
- the organic acid is an organic acid which does not form a chelate complex with a metal
- the above base is directly added to the above inactivated aqueous solution without neutralizing the above inactivated aqueous solution, Non-water soluble salts of organic acids can be precipitated. Therefore, the said method can each collect
- Aspect 4 The method according to any one of aspects 1 to 4, wherein the divalent or higher valent metal is selected from the group consisting of Mg, Ca, Ba, Fe, Ni, Cu, Zn and Al, and any combination thereof. Method.
- the divalent or higher valent metal is selected from the predetermined ones, the water solubility of the non-water-soluble salt of the formed organic acid becomes low, and the water-insoluble salt of the organic acid is removed in the subsequent mixture collecting step. The mixture of water and solid excrement is easily separated from the water-soluble salt.
- the acid in the organic acid production step is an acid having an acid dissociation constant of the organic acid (pK a, water) smaller acid dissociation constant than (pK a, water), one of the aspects 1-5 The method described in.
- the acid is an acid dissociation constant (pK a, water) the organic acid smaller acid dissociation constant (pK a, water) than for an acid having, in organic acid production step, the free organic acids It becomes easy to generate.
- the acid in the organic acid generation step is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, iodic acid and bromic acid, a free organic acid is easily generated in the organic acid generation step.
- a pH adjustment substep of adding the organic acid to the inactivated aqueous solution and adjusting the inactivated aqueous solution to a predetermined pH, and in the inactivated aqueous solution subjected to the pH adjustment substep The method further includes an increase in concentration step for increasing the concentration of the organic acid and the excrement in the inactivated aqueous solution by alternately repeating an inactivation substep of inactivating a new super absorbent polymer The method according to any one of to 7.
- the above method includes the concentration step of increasing the concentration of the organic acid and the excrement in the inactivated aqueous solution while inactivating the superabsorbent polymer in the inactivated aqueous solution before the precipitation step.
- the present inventors can inactivate the superabsorbent polymer even if the concentration of the excrement containing the basic substance in the inactivated aqueous solution increases. Found out. Therefore, by increasing the concentration of the organic acid and the excrement in the inactivated aqueous solution, the organic acid and the excrement can be efficiently recovered while maintaining the inactivation of the superabsorbent polymer.
- the inactivated aqueous solution containing excrement becomes easy to propagate bacteria present in the excrement, bacteria existing in the environment, etc. with the passage of time and with the concentration of organic acid and excrement becoming high. .
- the concentration increasing step further includes the sterilization substep, the bacteria in the inactivated aqueous solution can be suppressed to a predetermined amount.
- the inactivated aqueous solution is sterilized using a predetermined sterilization means, bacteria in the inactivated aqueous solution can be suppressed to a predetermined amount, and the inactivated aqueous solution is decolorized and deodorized. be able to.
- the predetermined sterilization means is a sterilization means which does not substantially remain in the inactivated water solution, the sterilization means does not easily remain in the organic acid aqueous solution to be recovered, and the step of separating the sterilization means is unnecessary. It becomes.
- a method for producing recycled pulp fibers from used absorbent articles while recycling organic acids that inactivate superabsorbent polymers A material containing pulp fibers and a superabsorbent polymer derived from the used absorbent article is immersed in an inactivated aqueous solution containing an organic acid having a predetermined pH to deactivate the superabsorbent polymer.
- Step A recycled pulp fiber forming step of forming the recycled pulp fiber from the material subjected to the inactivation step; Removing the material from the inactivated aqueous solution after the inactivation step, and adding a metal salt containing a divalent or higher metal or a base including a divalent or higher metal to the inactivated aqueous solution from which the material is removed
- An organic solution which adds an acid capable of generating a free organic acid and a water-insoluble salt and water to the above mixture to form an aqueous solution containing the organic acid, the water-insoluble salt and the solid excrement Acid generation step,
- the above method can produce recycled pulp fibers while recovering each of the organic acid and excrement from the used absorbent article and reusing the organic acid.
- the method further comprises a predetermined enrichment step after the inactivation step and before the precipitation step.
- the present inventors can adjust the inactivated aqueous solution to a predetermined pH so that the superabsorbent polymer can be inactivated even if the concentration of the excrement containing the basic substance in the inactivated aqueous solution increases. Found out. Therefore, by increasing the concentration of the organic acid and the excrement in the inactivated aqueous solution, the organic acid and the excrement can be efficiently recovered while maintaining the inactivation of the superabsorbent polymer.
- Aspect 13 The method according to aspect 12, wherein the step of increasing the concentration further comprises a sterilization substep of sterilizing the inactivated aqueous solution.
- the inactivated aqueous solution containing excrement tends to propagate bacteria present in the excrement, bacteria existing in the environment, etc. with the passage of time and with the increase in concentration of the organic acid and the excrement.
- the concentration increasing step further includes the sterilization substep, the bacteria in the inactivated aqueous solution can be suppressed to a predetermined amount.
- the sterilization substep since the inactivated aqueous solution is sterilized using a predetermined sterilization means, the amount of bacteria contained in the recycled pulp fiber can be reduced, and the recycled pulp fiber can be reduced by the inactivated aqueous solution. It is suppressed that it is colored and smelly, and thus, the number of steps for washing the recycled pulp fibers can be reduced. Further, in the above method, since the predetermined sterilization means is a sterilization means which does not substantially remain in the inactivated water solution, the sterilization means is unlikely to remain in the recycled pulp fiber, and the step of separating the sterilization means from the recycled pulp fiber is unnecessary. It becomes.
- Method of recovering organic acid and excrement from inactivated aqueous solution for super absorbent polymer containing excrement and organic acid of the present disclosure (hereinafter "method of recovering organic acid and excrement", or simply “recovery method”
- a method for producing recycled pulp fibers from recycled used absorbent articles while reusing the organic acid that deactivates the superabsorbent polymer (hereinafter referred to as “the method for producing recycled pulp fibers”) Will be described in detail below.
- the method for recovering organic acid and feces of the present disclosure includes the following steps.
- a precipitation step of depositing a non-water-soluble salt of an organic acid by adding a metal salt containing a divalent or higher metal or a base containing a divalent or higher metal to the inactivated aqueous solution (hereinafter referred to as “precipitation Sometimes referred to as “step”)
- a mixture collecting step of collecting a mixture of a non-water-soluble salt of an organic acid and a solid excrement derived from excrement from an inactivated aqueous solution having undergone a precipitation step (hereinafter referred to as “mixture collecting step” is there)
- a base containing a metal salt containing a divalent or higher metal or a metal including a divalent or higher metal (hereinafter referred to as “water insoluble” in an inactivated aqueous solution for superabsorbent polymer containing excrement and organic acid
- the non-water-soluble salt of the organic acid is precipitated by the addition of “salt forming salt”.
- a non-water-soluble salt of an organic acid by adding a metal salt containing a divalent or higher metal or a base containing a divalent or higher metal to the inactivated aqueous solution.
- an inactivated aqueous solution containing excrements [(ii) solid excrement and (iii) liquid excrement] and (iv) aqueous solution salt.
- the inactivated aqueous solution for superabsorbent polymer containing excrement and organic acid can be obtained by inactivating the superabsorbent polymer which absorbed excrement in an inactivated aqueous solution containing organic acid.
- excrement such as organic acid, feces, urine and the like are present.
- the organic acid is mainly dissolved in the above-mentioned inactivated aqueous solution, and among the above excrements, the liquid (iii) liquid excrement such as urine mainly dissolves in the inactivated aqueous solution, and feces And the like (ii) solid excrement are mainly dispersed in the inactivated aqueous solution.
- the organic acid is not particularly limited as long as it can adjust the inactivation aqueous solution to a predetermined pH at which the superabsorbent polymer can be inactivated, and as the organic acid, an acid group, For example, those having a carboxyl group, a sulfo group and the like can be mentioned.
- the organic acid having a sulfo group is referred to as a sulfonic acid, and the organic acid having a carboxyl group and not having a sulfo group is referred to as a carboxylic acid.
- organic acid from the viewpoint of carrying out the method for recovering the organic acid and excrement according to the present disclosure, in particular, in the organic acid generation step, a choice of acid capable of generating free organic acid and water-insoluble salt From the viewpoint of spreading, an organic acid having a carboxyl group, in particular, a carboxylic acid is preferable.
- the organic acid When the organic acid has a carboxyl group, the organic acid can have one or more carboxyl groups per molecule, and preferably has a plurality of carboxyl groups. By doing so, the organic acid is more likely to form a chelate complex with a divalent or higher metal, such as calcium, contained in the excrement and the like, and the ash content of recycled pulp fibers produced from used absorbent articles is reduced. It will be easier.
- a divalent or higher metal such as calcium
- organic acid examples include citric acid, tartaric acid, malic acid, succinic acid, oxalic acid (carboxylic acid having one or more carboxyl groups), gluconic acid (C 6 ), pentanoic acid (C 5 ), butanoic acid (C 4 ), propionic acid (C 3 ), glycolic acid (C 2 ), acetic acid (C 2 ), formic acid (C 1 ) (above, carboxylic acid having one carboxyl group), methanesulfonic acid, trifluoromethane sulfone
- acids, benzenesulfonic acid and p-toluenesulfonic acid aboveve, sulfonic acid).
- a non-water-soluble salt of an organic acid is added by adding a metal salt containing a metal having a valence of 2 or more (hereinafter sometimes simply referred to as "metal salt") to the inactivating aqueous solution.
- metal salt a metal salt containing a metal having a valence of 2 or more
- the inactivating aqueous solution may or may not be neutralized before adding the metal salt, but before adding the metal salt, the inactivating aqueous solution may be neutralized. It is preferable to neutralize the inactivated aqueous solution by adding a base (hereinafter sometimes referred to as "neutralizing base"). By doing so, the organic acid is less likely to form a chelate complex with the metal, and the recoverability of the organic acid is improved.
- the procedure of adding a metal salt after neutralization is particularly useful when the organic acid is an organic acid capable of forming a chelate complex with a metal.
- the base (a neutralizing base and a water-insoluble salt forming base) is a base based on the definition of Bronsted Lowry, that is, a substance capable of receiving proton H + .
- the neutralization base is a base containing a monovalent metal, such as lithium hydroxide, sodium hydroxide or potassium hydroxide. Is preferred. It is for suppressing that an organic acid forms a chelate complex.
- the inactivated aqueous solution for superabsorbent polymer containing excrement and organic acid is preferably 5.0 to 10.0, more preferably 6.0 to 9.0, by adding a neutralizing base. And, more preferably, it can be neutralized to a pH of 6.5 to 8.0. By doing so, when the organic acid is an organic acid capable of forming a chelate complex with a metal, it can be suppressed that the organic acid forms a chelate complex.
- the metal salt is not particularly limited as long as it can generate (i) a water-insoluble salt of an organic acid and (iv) a water-soluble salt by reacting with an organic acid.
- the above-mentioned metal salts are classified into “very soluble”, “soluble”, “slightly soluble” or “slightly insoluble” in “General Rule 29” of the “15th Amended Japanese Pharmacopoeia”. It is preferable to have. This is from the viewpoint of shortening the reaction time with the organic acid and making the unreacted metal salt less likely to remain in the water-insoluble salt of the organic acid (i).
- the metal salt is preferably a salt of an acid and a base containing a divalent or higher metal.
- a metal salt is added after neutralizing the inactivating aqueous solution, it is preferable that the divalent or higher metal constituting the metal salt has an ionization tendency close to that of the metal constituting the neutralization base. By doing so, the organic acid in the inactivated aqueous solution can be converted into (i) a water-insoluble salt of the organic acid in high yield.
- the acid capable of constituting the metal salt is preferably water-soluble, can be an organic acid or an inorganic acid, and is preferably an inorganic acid. It is from the viewpoint of recoverability of the organic acid.
- examples of the above-mentioned inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, iodic acid and bromic acid.
- Examples of the divalent or higher valent metal constituting the metal salt include a group consisting of Mg, Ca, Ba, Fe, Ni, Cu, Zn and Al, and any combination thereof.
- Water-insoluble salt of organic acid organic acid and divalent or higher valence metal
- organic acid and divalent or higher valence metal composed of an organic acid and a metal of bivalent or higher when the metal salt is comprised of a metal of divalent or higher valence The metal) tends to precipitate in the aqueous inactivation solution, and in the subsequent mixture collection step, makes it easier to (i) collect the water-insoluble salt of the organic acid.
- the metal salt is added in an amount such that it is preferably 0.8 or more equivalents, more preferably 0.9 or more equivalents, and still more preferably 1.0 or more equivalents with respect to the organic acid. Also, the metal salt is added in an amount such that it is preferably 3.0 times or less equivalent, more preferably 2.5 times or less equivalent, and still more preferably 2.0 times equivalent or less to the organic acid.
- Ru (I) From the viewpoint of efficiently forming a water-insoluble salt of an organic acid.
- the said equivalent means the equivalent between the valence of the metal which comprises a metal salt, and the number of acidic radicals which comprise an organic acid.
- the amount of the organic acid in the inactivating aqueous solution can be grasped by directly measuring the concentration of the organic acid in the inactivated aqueous solution to which the metal salt is added, and the total amount of organic acids added to the inactivated aqueous solution It can also be grasped from (the history) by deducting the amount of the inactivated aqueous solution (the amount of the discharged organic acid) discharged together with the super absorbent polymer, the pulp fiber and the like.
- the organic acid is an organic acid having a carboxyl group
- the acid can be, for example, hydrochloric acid, sulfuric acid, nitric acid or the like.
- the precipitation step S1 does not neutralize the inactivating aqueous solution, and the inactivating aqueous solution contains a divalent or higher metal.
- a water-soluble salt forming base By adding a water-soluble salt forming base, (i) a non-water-soluble salt of an organic acid can be precipitated. By doing so, the organic acid and the excrement can be recovered from the inactivated aqueous solution containing the excrement and the organic acid in a small number of steps.
- a metal more than bivalence which constitutes the above-mentioned base for non-water-soluble salts formation a group which consists of Mg, Ca, Ba, Fe, Ni, Cu, Zn, and Al, and arbitrary combination thereof is mentioned, for example.
- examples of the above-mentioned bases for water-insoluble salt formation include magnesium hydroxide, calcium hydroxide, copper hydroxide, zinc hydroxide and the like.
- the amount of the above-mentioned water-insoluble salt-forming base is preferably such that it is 0.8 or more equivalents, more preferably 0.9 or more equivalents, and still more preferably 1.0 or more equivalents with respect to the organic acid. Is added.
- the base for water-insoluble salt formation is preferably 3.0 times equivalent or less, more preferably 2.5 times equivalent or less, and still more preferably 2.0 times equivalent or less to the organic acid. Is added in (I) From the viewpoint of forming a water-insoluble salt of an organic acid.
- the said equivalent means the equivalent between the valence of the metal more than bivalence which comprises the base for non-water-soluble salt formation, and the number of acid groups which comprise an organic acid.
- organic acids which do not form chelate complexes with metals include pentanoic acid (C 5 ), butanoic acid (C 4 ), propionic acid (C 3 ), acetic acid (C 2 ), formic acid (C 1 ), etc. .
- organic acid capable of forming a chelate complex with a metal include citric acid, oxalic acid, tartaric acid, gluconic acid and the like.
- a water-insoluble salt of an organic acid is formed, the salt crystallizes and precipitates.
- the fine ones adhere to the surface of (i) the water-insoluble salt of the organic acid, and (i) the water-insoluble of the organic acid Is incorporated into the crystals of the salt and aggregates.
- the fine (ii) solid excrement is collected as a solid [ie, (i) water insoluble salt of organic acid and (ii) solid excrement], and a liquid [ie, (Iii) liquid excrement and (iv) water-soluble salt]
- a solid ie, (i) water insoluble salt of organic acid and (ii) solid excrement
- a liquid ie, (Iii) liquid excrement and (iv) water-soluble salt
- the inactivated aqueous solution after the precipitation step S1 contains (i) a non-water-soluble salt of an organic acid, (ii) a solid excrement, (iii) a liquid excrement, and (iv) a water-soluble salt.
- ⁇ Mixture Collection Step S2> a mixture of a non-water-soluble salt of an organic acid and a solid excrement is collected from the inactivated aqueous solution subjected to the precipitation step S1.
- inactivation includes (i) a water-insoluble salt of an organic acid, (ii) solid excrement, (iii) liquid excrement, and (iv) water-soluble salt. Separate the aqueous solution into solids [ie, water insoluble salts of (i) organic acids and (ii) solid excrements] and liquids [ie, (iii) liquid excrements and (iv) water soluble salts] Do.
- Organic acid generation step S3 an acid capable of generating a free organic acid and a non-water-soluble salt (hereinafter sometimes referred to as "free organic acid-forming acid") and water are added to the above mixture, An aqueous solution is formed comprising an organic acid and a water insoluble salt and solid waste.
- a free organic acid and acid are added to the solid (ie, (i) water-insoluble salt of organic acid and (ii) solid excrement), (v B) forming an aqueous solution comprising an organic acid, (vi) a water insoluble salt, and (ii) a solid excrement.
- the free organic acid-forming acid is not particularly limited as long as it can liberate the organic acid from the water-insoluble salt of the organic acid (i) and generate the water-insoluble salt, but the acid dissociation constant of the organic acid (pK a, water) is preferably an acid having a smaller acid dissociation constant than (pK a, water). By doing so, the organic acid is easily released in the organic acid generation step.
- the organic acid has a plurality of acid groups
- the above free organic acid-forming acid has an acid dissociation constant (pK a , water of the organic acid) smallest acid dissociation constant (pK a of) preferably has a smaller acid dissociation constant than water) (pK a, water). It is from a viewpoint of making it easy to form a free organic acid.
- the free organic acid-forming acid has a plurality of acid groups
- the acid dissociation constant of the free organic acid-forming acid ( pK a, the greatest acid dissociation constant of water) (pK a, water) is an acid dissociation constant of the organic acid (pK a, the smallest acid dissociation constant of water) (pK a, is less than water) preferable. It is from a viewpoint of the efficiency of the said free organic acid generation acid.
- Acid dissociation constant (pK a, water) of the organic acids acid having a smaller acid dissociation constant than (pK a, water) can be organic or inorganic acids, and is preferably an inorganic acid.
- examples of the above-mentioned inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, iodic acid and bromic acid.
- the acid dissociation constant (pk a , in water) the value described in the Electrochemical Handbook edited by the Institute of Electrochemical Society can be adopted. According to the Electrochemical Handbook, the acid dissociation constants (pk a , in water, 25 ° C.) of the major compounds are as follows: [Organic acid] - tartaric acid: 2.99 (pK a1), 4.44 (pK a2) - malic acid: 3.24 (pK a1), 4.71 (pK a2) Citric acid: 2.87 (pK a1), 4.35 (pK a2), 5.69 (pK a3) [Inorganic acid] -Sulfuric acid: 1.99
- the acid dissociation constant (pk a , in water) of an acid not described in the Electrochemical Handbook can be determined by measurement.
- an apparatus which can measure the acid dissociation constant (pk a , in water) of an acid for example, a compound physical property evaluation analysis system manufactured by Sirius, T3 can be mentioned.
- the free organic acid is added in an amount such that it is preferably 0.8 or more equivalents, more preferably 0.9 or more equivalents, and still more preferably 1.0 or more equivalents to the organic acid.
- Ru From the viewpoint of converting the non-water-soluble salt of an organic acid into (v) an organic acid in free state.
- the amount of free organic acid-forming acid is preferably not more than 2.0 times equivalent, more preferably not more than 1.5 times equivalent, and still more preferably not more than 1.3 times equivalent to the organic acid. Is added. This is from the viewpoint of making it difficult for the free organic acid-forming acid to remain in the aqueous solution of organic acid to be recovered (vii), and from the viewpoint of making the equipment less susceptible to corrosion.
- the said equivalent means the equivalent between the number of the acid groups of free organic acid generation acid, and the number of the acid groups which comprise an organic acid.
- the addition amount of the free organic acid can be determined based on (i) the composition of the water-insoluble salt of the organic acid and its dry weight. Also, the free organic acid-forming acid and water added in the organic acid-forming step S3 may be added separately to the above mixture and added together to the above mixture as an aqueous solution of free organic acid. May be
- Organic acid aqueous solution acquisition step S4 In the organic acid aqueous solution acquiring step S4, the water-insoluble salt and the solid excrement are removed from the aqueous solution to obtain an organic acid aqueous solution containing an organic acid. Specifically, in the organic acid aqueous solution obtaining step S4, a solid, ie, (vi) non-solid, is obtained from an aqueous solution containing (v) an organic acid, (vi) a non-water-soluble salt, and (ii) a solid excrement. The water-soluble salt and (ii) solid excrement are removed to obtain a liquid, ie, (v) an aqueous solution of an organic acid containing (v) an organic acid.
- the organic acid and waste collection method of the present disclosure can further include the following additional steps.
- A5 pH adjustment sub-step (hereinafter, may be referred to as “pH adjustment sub-step”) of adding an organic acid to the inactivated aqueous solution and adjusting the inactivated aqueous solution to a predetermined pH before the precipitation step;
- inactivation sub-step By alternately repeating the inactivation sub-step (hereinafter, may be referred to as “inactivation sub-step”) for inactivating a new superabsorbent polymer in the inactivated aqueous solution having undergone the pH adjustment sub-step,
- Enrichment step to increase the concentration of organic acid and excrement in activated aqueous solution (hereinafter sometimes referred to as “enrichment step”)
- the high concentration step may include a sterilization substep (hereinafter, may be referred to as “sterilization substep”) for sterilizing the inactivated aqueous solution.
- FIG. 2 shows a flowchar
- the concentration of the organic acid and the excrement in the inactivated aqueous solution is increased by alternately repeating the pH adjustment sub step S5a and the inactivation sub step S5b.
- the excrement retained by the superabsorbent polymer is repeatedly released into the inactivated aqueous solution to increase the concentration of the excrement in the inactivated aqueous solution.
- an organic acid is added to adjust the inactivated aqueous solution to a predetermined pH in the pH adjustment sub-step S5a. The concentration of organic acid in the inactivated aqueous solution increases.
- the organic acid is added to the inactivated aqueous solution for superabsorbent polymer, which contains an organic acid and excrement, and the inactivated aqueous solution is adjusted to a predetermined pH.
- the excrement contains basic components such as ammonia, so when the superabsorbent polymer is inactivated in the inactivated aqueous solution and excrement is released in the inactivated aqueous solution, the inactivated aqueous solution is PH tends to be high. Therefore, an organic acid is added to adjust the inactivated aqueous solution to a predetermined pH.
- the above-mentioned predetermined pH is preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and still more preferably 3.0 or less. If the predetermined pH is too high, the inactivation of the superabsorbent polymer may be insufficient. Also, the predetermined pH is preferably 0.5 or more, and more preferably 1.0 or more. When the predetermined pH is too low, for example, in the case of producing recycled pulp fibers from pulp fibers as well as inactivating and removing super absorbent polymers from materials containing pulp fibers and super absorbent polymers, recycled pulp The fibers may be damaged.
- the superabsorbent polymer holding excrement is inactivated.
- the inactivation sub-step S5b is performed at the predetermined pH described above.
- only the superabsorbent polymer can be inactivated, and the superabsorbent polymer in the material containing the superabsorbent polymer and the pulp fiber can be inactivated.
- the material include materials composed of a superabsorbent polymer and pulp fibers, such as an absorbent core and an absorbent article (for example, a crushed absorbent article).
- the high concentration step S5 may further include a sterilization sub-step S5c for sterilizing the inactivated aqueous solution.
- the inactivated aqueous solution containing excrement tends to propagate bacteria present in the excrement, bacteria existing in the environment, etc. with the passage of time and with the increase in concentration of the organic acid and the excrement.
- the sterilization sub-step S5c can be carried out using sterilization means known in the art and as sterilization means, for example, germicides, ozone, chlorine dioxide, hydrogen peroxide, ultraviolet light and radiation, and any of them A combination is mentioned.
- the radiation include electromagnetic radiation (X-ray and ⁇ -ray), particle beam ( ⁇ -ray, electron beam, proton beam, deuteron beam, ⁇ -ray and neutron beam) and the like.
- the sterilization sub-step S5c may sterilize the inactivated aqueous solution so that the number of general bacteria is preferably 100 or less, more preferably 50 or less, and even more preferably 20 or less. it can.
- the number of general bacteria is measured in accordance with JIS K 0350-10-10: 2002 "Test method for general bacteria in water and drainage".
- the sterilizing means is preferably a sterilizing means that does not substantially remain in the inactivated aqueous solution after the sterilizing substep S5c.
- the organic acid should be recovered (vii) in order not to leave the sterilization means in the organic acid aqueous solution.
- the sterilizing means may remain in the recycled pulp fiber And there may be a need to remove the sterilizing means from the recycled pulp fibers.
- Sterilizing means that do not substantially remain in the aqueous inactivation solution include germicides, ozone, chlorine dioxide, hydrogen peroxide, ultraviolet light and radiation, and any combination thereof.
- the high concentration step S5 can further include a decoloring step of decolorizing the inactivated aqueous solution using decolorizing means, a deodorizing step of deodorizing the inactivated aqueous solution using deodorizing means, and the like. It is because the said inactivation aqueous solution is easy to produce coloring, an odor, etc. which originate in excrement with high concentration-ization of the excrement.
- the decolorizing means is preferably a decoloring means which does not substantially remain in the inactivated aqueous solution after the decolorizing step. Moreover, it is preferable that the said deodorizing means is a deodorizing means which does not substantially remain
- sterilization means (decolorization means and deodorization means) which can be sterilized, decolorized and deodorized, and which do not substantially remain in the inactivated aqueous solution after sterilization substep S5c Included are ozone, chlorine dioxide, hydrogen peroxide, ultraviolet light and radiation, and any combination thereof.
- the sterilization sub-step S5c can be performed at an arbitrary position in the concentration increasing step S5, for example, before the pH adjustment sub-step S5a and / or after the pH adjustment sub-step S5a.
- the sterilization sub-step S5c can be performed once per cycle of the pH adjustment sub-step S5a and the inactivation sub-step S5b, and, for example, for the amount of bacteria, degree of coloration, odor degree, etc. Accordingly, for example, it can be carried out once per five cycles of pH adjustment sub-step S5a and inactivation sub-step S5b.
- the concentration of the organic acid in the inactivated aqueous solution is preferably 1.5 to 10.0% by mass, more preferably 2.0 to 8.0% by mass, and further preferably.
- the cycle of pH adjustment sub-step S5a and inactivation sub-step S5b can be repeated until the concentration of the acid is 2.3 to 6.0% by mass.
- the method for producing recycled pulp fiber of the present disclosure includes the following steps.
- (B1) A material containing pulp fibers and a superabsorbent polymer derived from used absorbent articles is immersed in an inactivated aqueous solution containing an organic acid having a predetermined pH to deactivate the superabsorbent polymer.
- Activation step hereinafter sometimes referred to as "inactivation step”
- (B2) A recycled pulp fiber forming step for forming recycled pulp fibers from a material that has undergone an inactivation step (hereinafter sometimes referred to as a "recycled pulp fiber forming step”)
- Precipitation step for precipitating a non-water-soluble salt of an organic acid
- a mixture collecting step of collecting a mixture of a non-water-soluble salt of an organic acid and a solid excrement derived from excrement from an inactivated aqueous solution having undergone a precipitation step (hereinafter referred to as “mixture collecting step” is there)
- An organic acid generating step of forming an aqueous solution containing an organic acid and an acid capable of forming a non-water-soluble salt, and water, to the mixture to form an aqueous solution containing the organic acid and the non-water-soluble salt and solid waste (Hereafter, it may be called "organ
- An organic acid aqueous solution acquiring step (hereinafter, may be referred to as "organic acid aqueous solution acquiring step” to obtain an organic acid aqueous solution containing an organic acid by removing a non-water-soluble salt and solid excrement from the aqueous solution)
- organic acid aqueous solution acquiring step to obtain an organic acid aqueous solution containing an organic acid by removing a non-water-soluble salt and solid excrement from the aqueous solution
- a re-inactivation step of performing an inactivation step using an organic acid aqueous solution as the above-mentioned inactivation aqueous solution (hereinafter sometimes referred to as a "re-inactivation step”)
- the method for producing recycled pulp fibers of the present disclosure can further include the following additional steps.
- a pH adjustment substep in which the organic acid is added to the inactivated aqueous solution to adjust the inactivated aqueous solution to a predetermined pH after the inactivation step and before the precipitation step (hereinafter referred to as "pH adjustment substep” And (in some cases) may be referred to as “inactivation sub-step” or the following inactivation sub-steps for inactivating new superabsorbent polymers in an inactivated aqueous solution having undergone a pH adjustment sub-step).
- a high concentration step to increase the concentration of organic acid and excrement in the inactivated aqueous solution by repeating hereinafter sometimes referred to as "high concentration step"
- the high concentration step may include a sterilization substep (hereinafter, may be referred to as “sterilization substep”) for sterilizing the inactivated aqueous solution.
- sterilization substep for sterilizing the inactivated aqueous solution.
- the material containing pulp fiber and super absorbent polymer derived from the used absorbent article is immersed in an inert aqueous solution containing an organic acid having a predetermined pH, and the super absorbent polymer is not Activate.
- materials containing pulp fibers and superabsorbent polymers derived from used absorbent articles include materials comprising superabsorbent polymers and pulp fibers (for example, an absorbent core), absorbent articles (for example, Crushed absorbent articles) and the like.
- the above-mentioned predetermined pH is preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and still more preferably 3.0 or less. If the predetermined pH is too high, the inactivation of the superabsorbent polymer may be insufficient. Also, the predetermined pH is preferably 0.5 or more, and more preferably 1.0 or more. When the predetermined pH is too low, for example, in the case of producing recycled pulp fibers from pulp fibers as well as inactivating and removing super absorbent polymers from materials containing pulp fibers and super absorbent polymers, recycled pulp The fibers may be damaged.
- the material containing the pulp fiber and the high water absorption polymer is stirred at room temperature for about 5 to 60 minutes to obtain the high water absorption polymer. It can be inactivated.
- the super absorbent polymer is not particularly limited as long as it is used as a super absorbent polymer in the art, and examples thereof include those containing an acid group such as a carboxyl group or a sulfo group. And those containing a carboxyl group are preferred.
- Examples of highly water-absorptive polymers containing a carboxyl group include those of polyacrylates and polyanhydrides, and examples of highly water-absorptive polymers containing sulfo and the like include polysulphonates. It can be mentioned.
- recycled pulp fibers are formed from the material that has undergone the inactivation step S101.
- the specific means for forming recycled pulp fibers is not particularly limited and can be carried out by methods known in the art.
- ozone gas is blown into an aqueous solution (for example, an inactivated aqueous solution) containing pulp fibers and a material containing an inactivated super absorbent polymer, which has undergone inactivation step S101.
- the inactivated superabsorbent polymer can be solubilized, and the pulp fibers can be sterilized, bleached, deodorized, etc. to form recycled pulp fibers.
- the high concentration step S103 (pH adjustment substep S103a, inactivation substep S103b, and sterilization substep S103c), precipitation step S104, mixture collection step S105, organic acid generation step S106, and organic acid aqueous solution acquisition step S107 respectively
- the step of increasing the concentration S5 (pH adjustment substep S5a, inactivation substep S5b, and sterilization substep S5c), precipitation step S1, mixture collection step S2, organic acid
- the process is the same as the generation step S3 and the organic acid aqueous solution acquisition step S4, so the description will be omitted.
- the organic acid aqueous solution obtained in the organic acid aqueous solution acquisition step S107 is used as an inactivation aqueous solution to perform an inactivation process as in the inactivation step S101.
- the organic acid aqueous solution obtained in the organic acid aqueous solution obtaining step S107 does not have the above-mentioned predetermined pH, it is adjusted to the above-mentioned predetermined pH and then used as the inactivating aqueous solution in the re-inactivation step S108. preferable.
- the organic acid aqueous solution obtained in the organic acid aqueous solution obtaining step S107 may be partially removed together with the material containing the pulp fiber and the super absorbent polymer, in which case, the organic acid aqueous solution obtaining step A new organic acid and water can be supplemented to the organic acid aqueous solution obtained by S107, and it can use for reactivation step S108 as an inactivation aqueous solution.
- a new material containing pulp fibers and a super absorbent polymer derived from the used absorbent article, which is different from the inactivation step S101, is treated with an organic acid-containing non-basic material having a predetermined pH. Immerse in activated aqueous solution to inactivate super absorbent polymer.
- FIG. 4 is a block diagram illustrating an example of a system 1 for implementing the present disclosure.
- the system 1 includes a bag removing device 11, a shredding device 12, a first separating device 13, a first dust removing device 14, a second dust removing device 15, a third dust removing device 16, and a second separating device 17.
- a third separation device 18, an ozone treatment device 19, a fourth separation device 20, a fifth separation device 21, an ozone treatment device 22, a pH adjustment device 23, and a water storage tank 24 are provided.
- FIG. 5 is a schematic view showing a configuration example of the bag removing device 11 and the crushing device 12 of FIG.
- the bag-breaking device 11 is filled with the inactivating aqueous solution B, and a hole is made in the collecting bag A which has been settled in the inactivating aqueous solution B.
- the bag tearing apparatus 11 includes a solution tank V and a perforation 50.
- the solution tank V stores the inactivating aqueous solution B.
- the hole making section 50 is provided in the solution tank V, and when the collection bag A is put in the solution tank V, a hole is made in the surface of the collection bag A in contact with the inactivating aqueous solution B.
- the piercing unit 50 includes a feeding unit 30 and a bag opening 40.
- the feed unit 30 feeds (pulls) the collection bag A (physically and forcibly) the inactivated aqueous solution B in the solution tank V.
- the feed unit 30 is, for example, a stirrer, and includes a stirring blade 33, a support shaft (rotary shaft) 32 supporting the stirring blade 33, and a drive device 31 rotating the support shaft 32 along an axis.
- the stirring blade 33 rotates around the rotation shaft (support shaft 32) by the drive device 31 to cause a swirling flow in the inactivated aqueous solution B.
- the feed unit 30 draws the collection bag A toward the bottom of the inactivating aqueous solution B (solution tank V) by the swirling flow.
- the tear-off portion 40 is disposed at the lower portion (preferably the bottom) of the solution tank V, and the tear-off blade 41, a support shaft (rotation shaft) 42 for supporting the tear-off blade 41, and the support shaft 42 And a driving device 43 which rotates along with it.
- the tear blade 41 makes a hole in the collection bag A moved to the lower part of the inactivated aqueous solution B (solution tank V) by rotating around the rotation shaft (support shaft 42) by the drive device 43.
- the crushing apparatus 12 crushes the used absorbent articles in the collection bag A sunk below the surface of the inactivating aqueous solution B together with the collection bag A.
- the crushing apparatus 12 includes a crushing unit 60 and a pump 63.
- the crushing unit 60 is connected to the solution tank V by a pipe 61, and the used absorbent articles (mixed liquid 91) in the collection bag A, which are sent out from the solution tank V together with the inactivating aqueous solution B, are collected together with the collection bag A. Disrupt in the inactivated aqueous solution B.
- the crusher 60 examples include a twin-screw crusher (example: twin-screw rotary crusher, twin-screw differential crusher, twin-screw shear crusher), and, for example, a sumi cutter (Sumitomo Heavy Industries Environment Co., Ltd.) Company-made).
- the pump 63 is connected to the crushing unit 60 by a pipe 62, and the crushed material obtained in the crushing unit 60 is pulled out from the crushing unit 60 together with the inactivating aqueous solution B (mixed liquid 92) and delivered to the next process.
- the crushed material includes materials including pulp fiber, super absorbent polymer, material of collecting bag A, film, non-woven fabric, elastic body and the like.
- the first separation device 13 stirs the mixture liquid 92 containing the crushed material obtained by the crushing device 12 and the inactivated aqueous solution, and mixes them while performing washing to remove dirt (excrements etc.) from the broken material. From the liquid 92, an inactivated aqueous solution 93 containing pulp fiber and super absorbent polymer is separated and delivered to the first dust removing device.
- Examples of the first separation device 13 include a washing tub and a dewatering tub and a washing machine provided with a water tub surrounding the same.
- a washing tank and dewatering tank (rotary drum) is used as a washing tank and sieving tank (separation tank).
- Examples of the washing machine include a horizontal washing machine ECO-22B (manufactured by Inamoto Seisakusho Co., Ltd.).
- the first dust remover 14 removes foreign matter present in the inactivated aqueous solution 93 containing pulp fiber and super absorbent polymer by a screen having a plurality of openings, and contains pulp fiber and super absorbent polymer with few foreign substances.
- the activated aqueous solution 94 is formed.
- Examples of the first dust remover 14 include a screen separator (coarse screen separator), and specifically, for example, a pack pulper (manufactured by Satomi Seisakusho Co., Ltd.).
- the second dust remover 15 removes finer foreign particles from the inactivated aqueous solution 94 containing pulp fibers and super absorbent polymer, which is less foreign particles, sent from the first dust remover 14 by a screen having a plurality of openings. Furthermore, an inactivated aqueous solution 95 containing pulp fibers and a superabsorbent polymer with less foreign matter is formed.
- the second dust remover 15 include a screen separator, and more specifically, for example, Lamo Screen (manufactured by Aikawa Tekko Co., Ltd.).
- the third dust remover 16 is further reduced in foreign matter from the inactivated aqueous solution 95 containing pulp fiber and super absorbent polymer, which is further reduced in foreign matter, and which is sent from the second dust remover 15 by centrifugal separation.
- An inactivated aqueous solution 96 comprising a superabsorbent polymer is formed.
- the third dust remover 16 include a cyclone separator, specifically, ACT low concentration cleaner (manufactured by Aikawa Iron Works Co., Ltd.).
- the second separation device 17 is activated by the screen having a plurality of openings, from the inactivated aqueous solution 96 containing pulp fiber and super absorbent polymer, which is further reduced in foreign matter and sent from the third dust removing device 16. It separates into the pulp fiber 97 containing an aqueous solution and a super absorbent polymer, and the inactivated aqueous solution 100 containing a super absorbent polymer.
- Examples of the second separation device 17 include a drum screen separator, and more specifically, for example, a drum screen dehydrator (manufactured by Toyo Screen Co., Ltd.).
- the third separator 18 comprises pulp fibers 97 delivered from the second separator 17 and a solid 98 including pulp fibers and a super absorbent polymer by a screen having a plurality of openings, and a super absorbent polymer remaining. The pressure is applied to the solid while separating it from the liquid containing the inactivated aqueous solution, and the superabsorbent polymer in the solid is crushed.
- a screw press dehydrator specifically, for example, a screw press dehydrator (manufactured by Kawaguchi Seiki Co., Ltd.) can be mentioned.
- the ozone treatment device 19 treats the solid 98 delivered from the third separation device 18 with an ozone aqueous solution containing ozone. As a result, the superabsorbent polymer is oxidatively decomposed to remove the superabsorbent polymer from the pulp fibers, and the aqueous ozone solution 99 containing recycled pulp fibers is discharged.
- the fourth separation device 20 separates the recycled pulp fibers from the aqueous ozone solution 99 treated by the ozone treatment device 19 using a screen having a plurality of openings.
- the fourth separation device 20 may be, for example, a screen separator.
- the fifth separation device 21, the ozone treatment device 22, the pH adjustment device 23, and the water storage tank 24 are devices for regenerating and reusing the inactivated aqueous solution used in the system 1.
- the fifth separation device 21 forms the inactivated aqueous solution 101 from which the highly absorbent polymer is removed from the inactivated aqueous solution 100 containing the highly absorbent polymer using a screen separator or the like.
- the ozone treatment device 22 sterilizes the inactivated aqueous solution 101 from which the superabsorbent polymer has been removed with ozone to form a sterilized inactivated aqueous solution 102.
- the pH adjusting device 23 adjusts the sterilized inactivated aqueous solution 102 to a predetermined pH to form a regenerated inactivated aqueous solution 103.
- the water storage tank 24 stores the surplus of the regenerated inactivated aqueous solution 103.
- Production Example 1 A total of 10 inactivation steps (inactivation step S101 ⁇ 1 times, inactivation sub-step S103 b ⁇ 9 times in the high concentration step S103) are performed according to the flowchart shown in FIG. I got one.
- the organic acid was citric acid
- the absorbent article was a used disposable diaper
- the superabsorbent polymer was sodium polyacrylate based.
- the initial pH of the inactivated aqueous solution was adjusted to 2.0
- the pH of the inactivated aqueous solution (second to tenth times) was adjusted to about 3.0 in the pH adjustment sub-step S103a.
- Inactivated aqueous solution No. 1 so that the number of general bacteria is less than 10 / mL with ozone after the inactivation step S101 and after the inactivation sub-step S103b in each of the high concentration steps S103.
- the sterilization step (sterilization sub-step S103c) is carried out, and after the first, fifth and tenth sterilization steps are completed, the inactivated aqueous solution No. 1 is removed.
- One time-lapsed sample (1 time, 5 times, 10 times) was sampled.
- the inactivated superabsorbent polymer was sampled.
- inactivated aqueous solution No. 1 having undergone a total of 10 inactivation steps. 1 contained 2.7% by mass of citric acid.
- inactivated aqueous solution No. 1 was prepared in the same manner as in Production Example 1 except that the sterilization step (sterilization sub-step S103c) was not performed. I prepared two. In addition, inactivated aqueous solution No. In No. 2, after completing the first, fifth and tenth inactivation steps, the inactivated aqueous solution No. 1 was prepared. Two time-lapse samples (1, 5, 10) were sampled. As a result of analysis, inactivated aqueous solution No. 2 contained 2.3% by mass of citric acid.
- Example 1 and 2 Inactivated aqueous solution No. 1 and inactivated aqueous solution No. 1 The number of common bacteria in each of two time-lapse samples (1, 5, 10) was determined. The results are shown in FIG. Moreover, the absorption factor (mass ratio) of the inactivated super-absorbent polymer sampled in Production Example 1 was as follows. First inactivation step S101: about 7.0 times second to tenth inactivation sub-step S103 b: about 22.0 times
- the number of common bacteria was 0 piece / g in any of the time-lapsed samples (the number of common bacteria of the undiluted sample itself was 0 / g).
- inactivated aqueous solution No. The time-lapsed sample of No. 1 (once, 5 times, 10 times) was treated with the inactivated aqueous solution No. 1 solution. There were less color and odor compared to each of the 2 time-lapsed samples (1, 5, 10). Therefore, it is suggested that it is preferable that the concentration step includes the sterilization sub-step when producing recycled pulp fibers when the number of concentration steps increases.
- the absorption capacity of the inactivated superabsorbent polymer was about 22.0 times. From this, it can be seen that the inactivation of the superabsorbent polymer is determined by the pH of the inactivated aqueous solution, and is less susceptible to the influence of the concentration step S103 (the influence of excreted excrement).
- Precipitation Step S104 Sodium hydroxide (solid) was added to 2,000 g of inactivated aqueous solution No. 1 to adjust the pH to 7. Next, while stirring the inactivated aqueous solution No. 1, the inactivated aqueous solution No. 1 is stirred. First, 32 g of calcium chloride as a metal salt was dissolved in (1) to precipitate calcium citrate as a non-water-soluble salt of an organic acid, and to aggregate fine (ii) solid excrement.
- ⁇ Organic acid generation step S106> (I) calcium citrate as a non-water-soluble salt of an organic acid and (ii) a solid excrement mixed with a 30% by mass aqueous sulfuric acid solution as a free organic acid-forming acid, calcium citrate (tetrahydrate And 120 g) were added so as to be 1.0 equivalent.
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Abstract
Description
例えば、特許文献1には、パルプ繊維および高吸水性ポリマーを含む使用済み衛生用品からパルプ繊維を回収し、衛生用品として再利用可能なリサイクルパルプを製造する方法であって、該方法が、使用済み衛生用品を、多価金属イオンを含む水溶液またはpHが2.5以下の酸性水溶液中で、使用済み衛生用品に物理的な力を作用させることによって、使用済み衛生物品をパルプ繊維とその他の素材に分解する工程、分解工程において生成したパルプ繊維とその他の素材の混合物からパルプ繊維を分離する工程、および分離されたパルプ繊維をpHが2.5以下のオゾン含有水溶液で処理する工程を含むことを特徴とする方法が開示されている。
また、本開示は、有機酸及び排泄物のそれぞれを回収するとともに、有機酸を再利用しつつ、使用済の吸収性物品からリサイクルパルプ繊維を製造する方法を提供することを目的とする。
また、本開示の使用済の吸収性物品からリサイクルパルプ繊維を製造する方法は、有機酸及び排泄物のそれぞれを回収するとともに、有機酸を再利用しつつ、リサイクルパルプ繊維を製造することができる。
・「非水溶性塩」
本明細書では、「非水溶性塩」に関する「非水溶性」は、「第十五改正日本薬局方」の「通則29」において、「溶けにくい」、「極めて溶けにくい」又は「ほとんど溶けない」に分類されることが好ましく、「極めて溶けにくい」又は「ほとんど溶けない」に分類されることがより好ましく、そして「ほとんど溶けない」に分類されることがさらに好ましい。
・溶けにくい : 100mL以上且つ 1,000mL未満
・極めて溶けにくい: 1,000mL以上且つ10,000mL未満
・ほとんど溶けない:10,000mL以上
本明細書では、「水溶性塩」に関する「水溶性」は、「第十五改正日本薬局方」の「通則29」において、「やや溶けやすい」、「溶けやすい」又は「極めて溶けやすい」に分類されることが好ましく、「溶けやすい」又は「極めて溶けやすい」に分類されることがより好ましく、そして「極めて溶けやすい」に分類されることがさらに好ましい。
・極めて溶けやすい: 1mL未満
・溶けやすい : 1mL以上且つ10mL未満
・やや溶けやすい :10mL以上且つ30mL未満
なお、「第十五改正日本薬局方」の「通則29」には、以下の分類がさらに存在する。
・やや溶けにくい :30mL以上且つ100mL未満
本明細書において、高吸水性ポリマー(Super Absorbent Polymer,SAP)に関する「不活化」は、排泄物を保持している高吸水性ポリマーが、好ましくは50倍以下、より好ましくは30倍以下、そしてさらに好ましくは25倍以下の吸収倍率を有するように調整すること、例えば、保持している排泄物を放出させること、不活化水溶液の吸収を抑制すること等を意味する。
上記吸収倍率は、以下の通り測定される。
(1)不活化した高吸水性ポリマーを、メッシュに入れて5分間吊るし、それらの表面に付着した水分を除去し、その乾燥前質量:m1(g)を測定する。
(3)吸収倍率(g/g)を、次の式:
吸収倍率(g/g)=100×m1/m2
により算出する。
なお、不活化水溶液は、高吸水性ポリマーを不活化するための水溶液を意味する。
[態様1]
有機酸及び排泄物を含む、高吸水性ポリマー用の不活化水溶液から、有機酸及び排泄物を回収する方法であって、
上記不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、有機酸の非水溶性塩を析出させる析出ステップ、
上記析出ステップを経た上記不活化水溶液から、上記有機酸の非水溶性塩と、上記排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ、
上記混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸、及び水を添加し、上記有機酸と、上記非水溶性塩及び上記固形排泄物とを含む水溶液を形成する有機酸生成ステップ、
上記水溶液から、上記非水溶性塩及び上記固形排泄物を除去し、上記有機酸を含む有機酸水溶液を得る有機酸水溶液取得ステップ、
を含むことを特徴とする、上記方法。
従って、上記方法は、排泄物及び有機酸を含む不活化水溶液から、有機酸と、排泄物とをそれぞれ回収することができる。
上記有機酸が、カルボキシル基を有する有機酸である、態様1に記載の方法。
上記方法では、有機酸がカルボキシル基を有する有機酸であるため、有機酸生成ステップにおいて、遊離の有機酸と、非水溶性塩とを生成しうる酸の選択肢を拡げることができ、ひいては有機酸の回収性を向上させることができる。
上記析出ステップにおいて、上記不活化水溶液を中和した後に、上記不活化水溶液に、上記金属塩を添加することにより、上記有機酸の非水溶性塩を析出させる、態様1又は2に記載の方法。
上記方法は、有機酸が、金属とキレート錯体を形成しうる有機酸である場合に、特に有用である。
上記有機酸が、金属とキレート錯体を形成しない有機酸であり、上記析出ステップにおいて、上記不活化水溶液に、上記塩基を添加することにより、上記有機酸の非水溶性塩を析出させる、態様1又は2に記載の方法。
上記2価以上の金属が、Mg,Ca,Ba,Fe,Ni,Cu,Zn及びAl、並びにそれらの任意の組み合わせからなる群から選択される、態様1~4のいずれか一項に記載の方法。
上記有機酸生成ステップにおける上記酸が、上記有機酸の酸解離定数(pKa,水中)よりも小さい酸解離定数(pKa,水中)を有する酸である、態様1~5のいずれか一項に記載の方法。
上記有機酸生成ステップにおける上記酸が、硫酸、塩酸、硝酸、ヨウ素酸及び臭素酸からなる群から選択される、態様1~6のいずれか一項に記載の方法。
上記析出ステップの前に、上記不活化水溶液に上記有機酸を添加し、上記不活化水溶液を所定のpHに調整するpH調整サブステップと、上記pH調整サブステップを経た上記不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップとを交互に繰り返すことにより、上記不活化水溶液中の上記有機酸及び上記排泄物を高濃度化させる高濃度化ステップをさらに含む、態様1~7のいずれか一項に記載の方法。
本発明者らは、不活化水溶液を所定のpHに調節すれば、不活化水溶液中の、塩基性物質を含む排泄物の濃度が高くなっても、高吸水性ポリマーを不活化することができることを見出した。
従って、不活化水溶液中の有機酸及び排泄物の濃度を高濃度化することにより、高吸水性ポリマーの不活化性を保持しながら、有機酸及び排泄物を効率よく回収することができる。
上記高濃度化ステップが、上記不活化水溶液を殺菌する殺菌サブステップをさらに含む、態様8に記載の方法。
上記方法では、高濃度化ステップが、殺菌サブステップをさらに含むため、不活化水溶液中の菌を所定の量に抑えることができる。
上記殺菌サブステップにおいて、上記不活化水溶液を、オゾン、二酸化塩素、過酸化水素、紫外線若しくは放射線、又はそれらの任意の組み合わせを用いて殺菌する、態様9に記載の方法。
使用済の吸収性物品から、高吸水性ポリマーを不活化する有機酸を再利用しつつ、リサイクルパルプ繊維を製造する方法であって、
上記使用済の吸収性物品に由来するパルプ繊維及び高吸水性ポリマーを含む資材を、所定のpHを有する、有機酸を含む不活化水溶液に浸漬し、上記高吸水性ポリマーを不活化する不活化ステップ、
上記不活化ステップを経た上記資材から、上記リサイクルパルプ繊維を形成するリサイクルパルプ繊維形成ステップ、
上記不活化ステップを経た上記不活化水溶液から上記資材を取出し、上記資材を取出した上記不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、有機酸の非水溶性塩を析出させる析出ステップ、
上記析出ステップを経た上記不活化水溶液から、上記有機酸の非水溶性塩と、上記排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ、
上記混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸、及び水を添加し、上記有機酸と、上記非水溶性塩及び上記固形排泄物とを含む水溶液を形成する有機酸生成ステップ、
上記水溶液から、上記非水溶性塩及び上記固形排泄物を除去し、上記有機酸を含む有機酸水溶液を得る有機酸水溶液取得ステップ、
上記不活化水溶液として、上記有機酸水溶液を用いた上記不活化ステップを行う再不活化ステップ、
を含むことを特徴とする、上記方法。
上記不活化ステップの後且つ上記析出ステップの前に、上記不活化水溶液に上記有機酸を添加し、上記不活化水溶液を所定のpHに調整するpH調整サブステップと、上記pH調整サブステップを経た上記不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップとを交互に繰り返すことにより、上記不活化水溶液中の上記有機酸及び上記排泄物を高濃度化させる高濃度化ステップをさらに含む、態様11に記載の方法。
本開示者らは、不活化水溶液を所定のpHに調節すれば、不活化水溶液中の、塩基性物質を含む排泄物の濃度が高くなっても、高吸水性ポリマーを不活化することができることを見出した。
従って、不活化水溶液中の有機酸及び排泄物の濃度を高濃度化することにより、高吸水性ポリマーの不活化性を保持しながら、有機酸及び排泄物を効率よく回収することができる。
上記高濃度化ステップが、上記不活化水溶液を殺菌する殺菌サブステップをさらに含む、態様12に記載の方法。
上記方法では、高濃度化ステップが、殺菌サブステップをさらに含むため、不活化水溶液中の菌を所定の量に抑えることができる。
上記殺菌サブステップにおいて、上記不活化水溶液を、オゾン、二酸化塩素、過酸化水素、紫外線若しくは放射線、又はそれらの任意の組み合わせを用いて殺菌する、態様13に記載の方法。
本開示の有機酸及び排泄物の回収方法は、以下のステップを含む。
(A1)不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、有機酸の非水溶性塩を析出させる析出ステップ(以下、「析出ステップ」と称する場合がある)
(A2)析出ステップを経た不活化水溶液から、有機酸の非水溶性塩と、排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ(以下、「混合物収集ステップ」と称する場合がある)
(A3)混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸、及び水を添加し、有機酸と、非水溶性塩及び固形排泄物とを含む水溶液を形成する有機酸生成ステップ(以下、「有機酸生成ステップ」と称する場合がある)
(A4)上記水溶液から、非水溶性塩及び固形排泄物を除去し、有機酸を含む有機酸水溶液を得る有機酸水溶液取得ステップ(以下、「有機酸水溶液取得ステップ」と称する場合がある)
また、図1に、本開示の回収方法を説明するためのフローチャートを示す。
析出ステップS1では、排泄物及び有機酸を含む、高吸水性ポリマー用の不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基(以下、「非水溶性塩生成用塩」と称する場合がある)を添加することにより、有機酸の非水溶性塩を析出させる。具体的には、析出ステップS1では、不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、(i)有機酸の非水溶性塩と、排泄物[(ii)固形排泄物及び(iii)液状排泄物]と、(iv)水溶液塩とを含む不活化水溶液を得る。
排泄物及び有機酸を含む、高吸水性ポリマー用の不活化水溶液には、有機酸、糞、尿等の排泄物等が存在している。有機酸は、上記不活化水溶液中に、主として、溶解しており、上記排泄物のうち、尿等の、液状の(iii)液状排泄物は、不活化水溶液中に、主として溶解し、そして便等の固形の(ii)固形排泄物は、不活化水溶液中に、主として、分散している。
上記金属塩は、「第十五改正日本薬局方」の「通則29」において、「極めて溶けやすい」、「溶けやすい」、「やや溶けやすい」又は「やや溶けにくい」に分類される溶解性を有することが好ましい。有機酸との反応時間を短くする、未反応の金属塩を、(i)有機酸の非水溶性塩中に残存しにくくする等の観点からである。
不活化水溶液を中和した後、金属塩を添加する場合には、上記金属塩を構成する2価以上の金属は、中和用塩基を構成する金属に近いイオン化傾向を有することが好ましい。そうすることにより、不活化水溶液中の有機酸を、高収率で(i)有機酸の非水溶性塩に変化させることができる。
なお、上記当量は、金属塩を構成する金属の価数と、有機酸を構成する酸基の数との間の当量を意味する。
また、不活化水溶液中の有機酸の量が不明な場合等には、有機酸に対して過剰量と思われる金属塩を添加し、余剰の金属塩を、続く混合物収集ステップ、有機酸水溶液取得ステップ等において、有機酸水溶液と分離してもよい。
上記非水溶性塩生成用塩基としては、例えば、水酸化マグネシウム、水酸化カルシウム、水酸化銅、水酸化亜鉛等が挙げられる。
なお、上記当量は、非水溶性塩生成用塩基を構成する2価以上の金属の価数と、有機酸を構成する酸基の数との間の当量を意味する。
金属とキレート錯体を形成しうる有機酸としては、例えば、クエン酸、シュウ酸、酒石酸、グルコン酸等が挙げられる。
混合物収集ステップS2では、析出ステップS1を経た不活化水溶液から、有機酸の非水溶性塩と、固形排泄物との混合物を収集する。
具体的には、混合物収集ステップS2では、(i)有機酸の非水溶性塩と、(ii)固形排泄物と、(iii)液状排泄物と、(iv)水溶性塩とを含む不活化水溶液を、固形物[すなわち、(i)有機酸の非水溶性塩及び(ii)固形排泄物]と、液状物[すなわち、(iii)液状排泄物及び(iv)水溶性塩]とに分離する。
有機酸生成ステップS3では、上記混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸(以下、「遊離有機酸生成酸」と称する場合がある)、及び水を添加し、有機酸と、非水溶性塩及び固形排泄物とを含む水溶液を形成する。具体的には、有機酸生成ステップS3では、固形物[すなわち、(i)有機酸の非水溶性塩及び(ii)固形排泄物]に、遊離有機酸生成酸及び水を添加し、(v)有機酸と、(vi)非水溶性塩と、(ii)固形排泄物とを含む水溶液を形成する。
電気化学便覧によると、主要な化合物の酸解離定数(pka,水中,25℃)は、以下の通りである。
[有機酸]
・酒石酸:2.99(pKa1),4.44(pKa2)
・リンゴ酸:3.24(pKa1),4.71(pKa2)
・クエン酸:2.87(pKa1),4.35(pKa2),5.69(pKa3)
[無機酸]
・硫酸:1.99
なお、上記当量は、遊離有機酸生成酸の酸基の数と、有機酸を構成する酸基の数との間の当量を意味する。
また、有機酸生成ステップS3にて添加される遊離有機酸生成酸及び水は、上記混合物に、別個に添加されてもよく、そして遊離有機酸生成酸の水溶液として、上記混合物に一緒に添加されてもよい。
有機酸水溶液取得ステップS4では、上記水溶液から、非水溶性塩及び固形排泄物を除去し、有機酸を含む有機酸水溶液を得る。具体的には、有機酸水溶液取得ステップS4では、(v)有機酸と、(vi)非水溶性塩と、(ii)固形排泄物とを含む水溶液から、固形物、すなわち、(vi)非水溶性塩及び(ii)固形排泄物を除去し、液状物、すなわち、(v)有機酸を含む(vii)有機酸水溶液を得る。
(A5)析出ステップの前の、不活化水溶液に有機酸を添加し、不活化水溶液を所定のpHに調整するpH調整サブステップ(以下、「pH調整サブステップ」と称する場合がある)と、pH調整サブステップを経た不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップ(以下、「不活化サブステップ」と称する場合がある)とを交互に繰り返すことにより、不活化水溶液中の有機酸及び排泄物を高濃度化させる高濃度化ステップ(以下、「高濃度化ステップ」と称する場合がある)
上記高濃度化ステップは、不活化水溶液を殺菌する殺菌サブステップ(以下、「殺菌サブステップ」と称する場合がある)を含むことができる。
図2に、上記追加のステップを説明するためのフローチャートを示す。
高濃度化ステップS5では、pH調整サブステップS5aと、不活化サブステップS5bとを交互に繰り返すことにより、不活化水溶液中の有機酸及び排泄物を高濃度化させる。
不活化サブステップS5bを繰り返すことにより、高吸水性ポリマーが保持する排泄物を、不活化水溶液中に繰り返し放出させ、不活化水溶液中の排泄物を高濃度化させる。また、排泄物の高濃度化に合わせて、不活化水溶液のpHが高くなるため、pH調整サブステップS5aにおいて、不活化水溶液を所定のpHに調整するために有機酸を添加することになり、不活化水溶液中の有機酸が高濃度化していく。
また、上記所定のpHは、好ましくは0.5以上、そしてより好ましくは1.0以上である。上記所定のpHが低すぎると、例えば、パルプ繊維及び高吸水性ポリマーを含む資材から、高吸水性ポリマーを不活化し、除去するととともに、パルプ繊維からリサイクルパルプ繊維を製造する場合に、リサイクルパルプ繊維が損傷するおそれがある。
不活化サブステップS5bでは、高吸水性ポリマーのみを不活化することができ、そして高吸水性ポリマー及びパルプ繊維を含む資材中の高吸水性ポリマーを不活化することができる。上記資材としては、高吸水性ポリマー及びパルプ繊維から成る資材、例えば、吸収コア、吸収性物品(例えば、破砕された吸収性物品)が挙げられる。
上記放射線としては、電磁放射線(X線及びγ線)、粒子線(β線、電子線、陽子線、重陽子線、α線及び中性子線)等が挙げられる。
なお、一般細菌の個数は、JIS K0350-10-10:2002「用水・排水中の一般細菌試験方法」に従って測定される。
不活化水溶液に実質的に残存しない殺菌手段としては、殺菌剤、オゾン、二酸化塩素、過酸化水素、紫外線及び放射線、並びにそれらの任意の組み合わせが挙げられる。
本開示のリサイクルパルプ繊維の製造方法は、以下のステップを含む。
(B1)使用済の吸収性物品に由来するパルプ繊維及び高吸水性ポリマーを含む資材を、所定のpHを有する、有機酸を含む不活化水溶液に浸漬し、高吸水性ポリマーを不活化する不活化ステップ(以下、「不活化ステップ」と称する場合がある)
(B2)不活化ステップを経た資材から、リサイクルパルプ繊維を形成するリサイクルパルプ繊維形成ステップ(以下、「リサイクルパルプ繊維形成ステップ」と称する場合がある)
(B4)析出ステップを経た不活化水溶液から、有機酸の非水溶性塩と、排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ(以下、「混合物収集ステップ」と称する場合がある)
(B5)混合物に、有機酸と、非水溶性塩とを形成しうる酸、及び水を添加し、有機酸と、非水溶性塩及び固形排泄物とを含む水溶液を形成する有機酸生成ステップ(以下、「有機酸生成ステップ」と称する場合がある)
(B7)上記不活化水溶液として、有機酸水溶液を用いた不活化ステップを行う再不活化ステップ(以下、「再不活化ステップ」と称する場合がある)
(B8)不活化ステップの後且つ析出ステップの前に、不活化水溶液に有機酸を添加し、不活化水溶液を所定のpHに調整するpH調整サブステップ(以下、「pH調整サブステップ」と称する場合がある)と、pH調整サブステップを経た不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップ以下、「不活化サブステップ」と称する場合がある)とを交互に繰り返すことにより、不活化水溶液中の有機酸及び排泄物を高濃度化させる高濃度化ステップ(以下、「高濃度化ステップ」と称する場合がある)
図3に、本開示のリサイクルパルプ繊維の製造方法を説明するためのフローチャートを示す。
不活化ステップS101では、使用済の吸収性物品に由来するパルプ繊維及び高吸水性ポリマーを含む資材を、所定のpHを有する、有機酸を含む不活化水溶液に浸漬し、高吸水性ポリマーを不活化する。
上述のように、使用済の吸収性物品に由来するパルプ繊維及び高吸水性ポリマーを含む資材としては、高吸水性ポリマー及びパルプ繊維から成る資材(例えば、吸収コア)、吸収性物品(例えば、破砕された吸収性物品)等が挙げられる。
また、上記所定のpHは、好ましくは0.5以上、そしてより好ましくは1.0以上である。上記所定のpHが低すぎると、例えば、パルプ繊維及び高吸水性ポリマーを含む資材から、高吸水性ポリマーを不活化し、除去するととともに、パルプ繊維からリサイクルパルプ繊維を製造する場合に、リサイクルパルプ繊維が損傷するおそれがある。
カルボキシル基を含む高吸水性ポリマーとしては、例えば、ポリアクリル酸塩系、ポリ無水マレイン酸塩系のものが挙げられ、スルホ基等を含む高吸水性ポリマーとしては、ポリスルホン酸塩系のものが挙げられる。
リサイクルパルプ繊維形成ステップS102では、不活化ステップS101を経た資材から、リサイクルパルプ繊維を形成する。リサイクルパルプ繊維を形成する具体的な手段は特に制限されず、当技術分野で公知の方法で実施することができる。
例えば、特許文献1に記載されるように、不活化ステップS101を経た、パルプ繊維と、不活化した高吸水性ポリマーを含む資材を含む水溶液(例えば、不活化水溶液)中に、オゾンガスを吹き込むことにより、不活化した高吸水性ポリマーを可溶化させるとともに、パルプ繊維を殺菌、漂白、脱臭等し、リサイクルパルプ繊維を形成することができる。
再不活化ステップS108では、有機酸水溶液取得ステップS107で得られた有機酸水溶液を、不活化水溶液として用いて、不活化ステップS101と同様に、不活化処理を行う。
有機酸水溶液取得ステップS107で得られた有機酸水溶液が上述の所定のpHを有しない場合には、上述の所定のpHに調整した上で、不活化水溶液として、再不活化ステップS108に用いることが好ましい。
システム1は、破袋装置11と、破砕装置12と、第1分離装置13と、第1除塵装置14と、第2除塵装置15と、第3除塵装置16と、第2分離装置17と、第3分離装置18と、オゾン処理装置19と、第4分離装置20と、第5分離装置21と、オゾン処理装置22と、pH調整装置23と、貯水槽24とを備える。
第5分離装置21は、高吸水性ポリマーを含む不活化水溶液100から、スクリーン分離機等を用いて、高吸水性ポリマーが除去された不活化水溶液101を形成する。
オゾン処理装置22は、高吸水性ポリマーが除去された不活化水溶液101を、オゾンで殺菌処理して、殺菌処理された不活化水溶液102を形成する。pH調整装置23は、殺菌処理された不活化水溶液102を、所定のpHに調整して、再生された不活化水溶液103を形成する。貯水槽24は、再生された不活化水溶液103のうちの余剰分を貯留する。
[製造例1]
図3に記載のフローチャートに従って、計10回の不活化ステップ(不活化ステップS101×1回,高濃度化ステップS103における不活化サブステップS103b×9回)を実施した不活化水溶液No.1を得た。有機酸はクエン酸であり、吸収性物品は、使用済の使い捨ておむつであり、高吸水性ポリマーは、ポリアクリル酸ナトリウム系であった。また、不活化水溶液(1回目)の初期pHを2.0に調整し、pH調整サブステップS103aでは、不活化水溶液(2回目~10回目)のpHを約3.0に調整した。
分析を行ったところ、計10回の不活化ステップを経た不活化水溶液No.1は、クエン酸を2.7質量%含んでいた。
殺菌ステップ(殺菌サブステップS103c)を実施しなかった以外は、製造例1と同様にして、不活化水溶液No.2を準備した。
なお、不活化水溶液No.2では、1回目、5回目及び10回目の不活化ステップを終えた後に、不活化水溶液No.2の経時サンプル(1回,5回,10回)をサンプリングした。
分析を行ったところ、不活化水溶液No.2は、クエン酸を2.3質量%含んでいた。
不活化水溶液No.1及び不活化水溶液No.2のそれぞれの経時サンプル(1回,5回,10回)中の一般細菌の個数を測定した。結果を図6に示す。
また、製造例1においてサンプリングされた、不活化した高吸水性ポリマーの吸収倍率(質量比)は以下の通りであった。
・第1回目の不活化ステップS101:約7.0倍
・第2回目~第10回目の不活化サブステップS103b:約22.0倍
従って、高濃度化ステップの数が増える場合であって、リサイクルパルプ繊維を製造するときには、高濃度化ステップが、殺菌サブステップを含むことが好ましいことが示唆される。
<析出ステップS104>
2,000gの不活化水溶液No.1に、水酸化ナトリウム(固体)を加え、pHを7に調整した。次いで、不活化水溶液No.1を攪拌しながら、不活化水溶液No.1に、金属塩としての塩化カルシウム32gを溶解させ、(i)有機酸の非水溶性塩としてのクエン酸カルシウムを析出させるとともに、微細な(ii)固形排泄物を凝集させた。
塩化カルシウムの添加から24時間静置した後、メッシュ状フィルターを用いて、不活化水溶液No.1を固液分離することにより、(i)有機酸の非水溶性塩としてのクエン酸カルシウム(四水和物)と、(ii)固形排泄物との混合物(湿潤状態)を得て、混合物(湿潤状態)を120℃で10分乾燥することにより、混合物(乾燥状態)120gを得た。
(i)有機酸の非水溶性塩としてのクエン酸カルシウムと、(ii)固形排泄物との混合物に、遊離有機酸生成酸としての30質量%硫酸水溶液を、クエン酸カルシウム(四水和物)120gと1.0倍当量になるように添加した。具体的には、混合物(乾燥状態)120gが全てクエン酸カルシウム(四水和物)(=0.21mol)であるとみなして、30質量%硫酸水溶液を、そのH+の総モル数が、クエン酸カルシウム(四水和物)0.21mol中に存在するカルボキシル基の総モル数である1.26molと1.0倍当量の1.26mol(硫酸のモル数が0.63mol)となるように、上記混合物(乾燥状態)に添加した。
混合物水溶液中では、30質量%硫酸水溶液の添加とともに、(vi)非水溶性塩としての硫酸カルシウムの沈殿が形成された。
混合物水溶液を、メッシュ状フィルターで固液分離することにより、(vii)有機酸水溶液としてのクエン酸水溶液約65gを得た。クエン酸水溶液のpHは、2.1であった。
S2 混合物収集ステップ
S3 有機酸生成ステップ
S4 有機酸水溶液取得ステップ
S5 高濃度化ステップ
S5a pH調整サブステップ
S5b 不活化サブステップ
S5c 殺菌サブステップ
S101 不活化ステップ
S102 リサイクルパルプ繊維形成ステップ
S103 高濃度化ステップ
S103a pH調整サブステップ
S103b 不活化サブステップ
S103c 殺菌サブステップ
S104 析出ステップ
S105 混合物収集ステップ
S106 有機酸生成ステップ
S107 有機酸水溶液取得ステップ
S108 再不活化ステップ
11 破袋装置
12 破砕装置
13 第1分離装置
14 第1除塵装置
15 第2除塵装置
16 第3除塵装置
17 第2分離装置
18 第3分離装置
19 オゾン処理装置
20 第4分離装置
21 第5分離装置
22 オゾン処理装置
23 pH調整装置
24 貯水槽
Claims (14)
- 有機酸及び排泄物を含む、高吸水性ポリマー用の不活化水溶液から、有機酸及び排泄物を回収する方法であって、
前記不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、有機酸の非水溶性塩を析出させる析出ステップ、
前記析出ステップを経た前記不活化水溶液から、前記有機酸の非水溶性塩と、前記排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ、
前記混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸、及び水を添加し、前記有機酸と、前記非水溶性塩及び前記固形排泄物とを含む水溶液を形成する有機酸生成ステップ、
前記水溶液から、前記非水溶性塩及び前記固形排泄物を除去し、前記有機酸を含む有機酸水溶液を得る有機酸水溶液取得ステップ、
を含むことを特徴とする、前記方法。 - 前記有機酸が、カルボキシル基を有する有機酸である、請求項1に記載の方法。
- 前記析出ステップにおいて、前記不活化水溶液を中和した後に、前記不活化水溶液に、前記金属塩を添加することにより、前記有機酸の非水溶性塩を析出させる、請求項1又は2に記載の方法。
- 前記有機酸が、金属とキレート錯体を形成しない有機酸であり、前記析出ステップにおいて、前記不活化水溶液に、前記塩基を添加することにより、前記有機酸の非水溶性塩を析出させる、請求項1又は2に記載の方法。
- 前記2価以上の金属が、Mg,Ca,Ba,Fe,Ni,Cu,Zn及びAl、並びにそれらの任意の組み合わせからなる群から選択される、請求項1~4のいずれか一項に記載の方法。
- 前記有機酸生成ステップにおける前記酸が、前記有機酸の酸解離定数(pKa,水中)よりも小さい酸解離定数(pKa,水中)を有する酸である、請求項1~5のいずれか一項に記載の方法。
- 前記有機酸生成ステップにおける前記酸が、硫酸、塩酸、硝酸、ヨウ素酸及び臭素酸からなる群から選択される、請求項1~6のいずれか一項に記載の方法。
- 前記析出ステップの前に、前記不活化水溶液に前記有機酸を添加し、前記不活化水溶液を所定のpHに調整するpH調整サブステップと、前記pH調整サブステップを経た前記不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップとを交互に繰り返すことにより、前記不活化水溶液中の前記有機酸及び前記排泄物を高濃度化させる高濃度化ステップをさらに含む、請求項1~7のいずれか一項に記載の方法。
- 前記高濃度化ステップが、前記不活化水溶液を殺菌する殺菌サブステップをさらに含む、請求項8に記載の方法。
- 前記殺菌サブステップにおいて、前記不活化水溶液を、オゾン、二酸化塩素、過酸化水素、紫外線若しくは放射線、又はそれらの任意の組み合わせを用いて殺菌する、請求項9に記載の方法。
- 使用済の吸収性物品から、高吸水性ポリマーを不活化する有機酸を再利用しつつ、リサイクルパルプ繊維を製造する方法であって、
前記使用済の吸収性物品に由来するパルプ繊維及び高吸水性ポリマーを含む資材を、所定のpHを有する、有機酸を含む不活化水溶液に浸漬し、前記高吸水性ポリマーを不活化する不活化ステップ、
前記不活化ステップを経た前記資材から、前記リサイクルパルプ繊維を形成するリサイクルパルプ繊維形成ステップ、
前記不活化ステップを経た前記不活化水溶液から前記資材を取出し、前記資材を取出した前記不活化水溶液に、2価以上の金属を含む金属塩、又は2価以上の金属を含む塩基を添加することにより、有機酸の非水溶性塩を析出させる析出ステップ、
前記析出ステップを経た前記不活化水溶液から、前記有機酸の非水溶性塩と、前記排泄物に由来する固形排泄物との混合物を収集する混合物収集ステップ、
前記混合物に、遊離の有機酸と、非水溶性塩とを生成しうる酸、及び水を添加し、前記有機酸と、前記非水溶性塩及び前記固形排泄物とを含む水溶液を形成する有機酸生成ステップ、
前記水溶液から、前記非水溶性塩及び前記固形排泄物を除去し、前記有機酸を含む有機酸水溶液を得る有機酸水溶液取得ステップ、
前記不活化水溶液として、前記有機酸水溶液を用いた前記不活化ステップを行う再不活化ステップ、
を含むことを特徴とする、前記方法。 - 前記不活化ステップの後且つ前記析出ステップの前に、前記不活化水溶液に前記有機酸を添加し、前記不活化水溶液を所定のpHに調整するpH調整サブステップと、前記pH調整サブステップを経た前記不活化水溶液中で、新たな高吸水性ポリマーを不活化させる不活化サブステップとを交互に繰り返すことにより、前記不活化水溶液中の前記有機酸及び前記排泄物を高濃度化させる高濃度化ステップをさらに含む、請求項11に記載の方法。
- 前記高濃度化ステップが、前記不活化水溶液を殺菌する殺菌サブステップをさらに含む、請求項12に記載の方法。
- 前記殺菌サブステップにおいて、前記不活化水溶液を、オゾン、二酸化塩素、過酸化水素、紫外線若しくは放射線、又はそれらの任意の組み合わせを用いて殺菌する、請求項13に記載の方法。
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